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Quote: Originally posted by Adrian Jones I was leaving that one alone as well. If they were truly indistinguishable then the higher bit rate wouldn't even exist. As with most things, it was a trade off of higher quality versus space. What I meant by that was that if listened to blindly, most people are not going to know whether they are hearing 768 or 1536. Cutting the audio bit rate in half allows for greater quality on the video side with little loss to the audio by comparison.

Quote: The only part I usually tend to disagree with is "the audible difference between 768 and 1536 is virtually indistinguishable to the human ear". Thats a discussion I don't even care to start, but the point is well taken.

I was leaving that one alone as well. If they were truly indistinguishable then the higher bit rate wouldn't even exist. As with most things, it was a trade off of higher quality versus space.

Very impressive knowledge you have of encoding Matt. That certainly clears up my lack of understanding of the process. Thanks for the information. The only part I usually tend to disagree with is "the audible difference between 768 and 1536 is virtually indistinguishable to the human ear". Thats a discussion I don't even care to start, but the point is well taken.

Quote: Originally posted by Keith Gump I don't think it has less to do with that at all. Its a matter of space limitations. DTS takes up more room that DD...especially full range DTS. I agree that total disc size plays a major part, but audio tracks primarily take up a much smaller portion of the available space on the DVD than you may realize, and the difference between Dolby Digital 5.1 and DTS 5.1 is only a couple of hundred MBs depending on the length of the film. The overall bit rate of the playable stream plays an equal part in how films are transferred to DVD-Video as there is a limitation to overall bit rate that the DVD format can handle and be properly played back.

As a general rule, the maximum total bit rate for an MPEG-2 video stream and all associated audio streams is 10.08 MBps. Not unlike variably encoding an MP3 file, MPEG-2 encoding is performed using a variable bit rate algorithm where both a minimum and maximum bit rate is used to allocate more data to frames that require it and less to those that don't so that that quality remains constant while keeping the size of the resulting file manageable. If the encoder sets the maximum bit rate to 9.8 MBps, which is the industry standard for the maximum allowable bit rate for MPEG-2 video, then the maximum stream size for the audio tracks must be no more than 280 Kbps. Otherwise, the total stream will cause errors on playback if the maximum bit rate is surpassed too often (it can be exceeded slightly from time to time without problems) and render the resulting DVD-Video unplayable.

So as an example let’s take a look at the Superbit edition of Spider-Man 2. This disc contains an MPEG-2 video stream at an unknown, maximum bit rate and a total file size of 5.73 GB along with a 448 Kbps Dolby Digital 5.1 channel and a 768 Kbps DTS 5.1 channel at file sizes of 432 and 731 MBs each for a total video and audio file size of 6.88 GB for the 127 minute film. Subtitles are also included in the overall stream, but are usually of little consequence so I’ll leave them out for the purposes of this example. Adding the two audio streams together produces a total stream of 1.216 Mbps, leaving the maximum bit rate for the MPEG-2 video stream as 8.864 Mbps during encoding. Adding any additional audio tracks to the film would result in the maximum bit rate for the MPEG-2 video stream to drop accordingly. Likewise, removing one of the tracks would enable the video bit rate to be increased closer to the maximum of 9.8 Mbps allowed for video. Since I obviously wasn’t present at the time this film was encoded to MPEG-2 video I can’t state the exact maximum bit rate, but my guess is that it was fairly close to the 8.864 Mbps stated above. It doesn’t matter how much available space is on the DVD disc itself, the encoded MPEG-2 video cannot be of any greater quality because the encoder cannot exceed these limitations when transferring the film to the DVD-Video format. Even the Superbit of Spider-Man 2 which has a greater running time than most films' average of 100 minutes leaves plenty of open space on the disc.

Now all that being stated, most single disc DVD packages that contain a fair amount of special features and a greater number of audio tracks will not be able to, depending on the length of the film, use the maximum bit rate because of the available space on the disc unless the bulk of the features are moved to a second disc, so there is where the disc space comes into play. In a perfect world every DVD would be encoded to use the maximum video bit rate and worry about the special features after, but as we all know that isn't the case so there is some give and take with how the studios manufacture DVDs.

On the subject of so-called uncompressed DTS, audio tracks at 1536 Kbps are so few and far between that you will find it difficult to find more than a handful. Nearly all DTS 5.1 tracks are 768 Kbps because the audible difference between 768 and 1536 is virtually indistinguishable to the human ear and cutting the rate in half keeps the video bit rate at a higher level as described in the example above.

Interesting. I'll keep all ypur comments in mind, and of course the obvious stated by Chris, because this is a DVD review site. Forgot about that! And Adam, so true about your statements that we spend thousands of dollars on the top equipment so, we expect the best out of the dvd's from the studios.

Quote: Originally posted by Keith Gump I agree with Worst Nightmare. You must realize, high quality video and sound was the hype for DVD, before DVD even hit the market. However, the industry is not making the best use of the medium. Wasteful extra features, commentaries, and previews take away from what could have been a better quality release. Most extra features could be on another disc, yet the industry usually tries to fit it all on one disc, to avoid a second disc. It has less to do with that and more do do with the limitations of the overall combined video and audio bitrate inherent to the DVD format.

I agree with Worst Nightmare. You must realize, high quality video and sound was the hype for DVD, before DVD even hit the market. However, the industry is not making the best use of the medium. Wasteful extra features, commentaries, and previews take away from what could have been a better quality release. Most extra features could be on another disc, yet the industry usually tries to fit it all on one disc, to avoid a second disc.

Quote: Originally posted by Mark Lim Why is it that you people go into so much technical jargon like you feel the picture quality and sound on a DVD must be 100% perfect?!!

I feel that as long as the picture is good enough to see and the sound is good, I'm happy with it. This does not include Pirated DVD's. I do not accept such poor quality.When people like us spend thousands on home theatre equipment, why would we not expect the best? If I am going to spend money on something I want it to be the best quality no matter what it is and I will not accept that with the technology behind this medium that the studios cannot give us what we want all the time! Just my rant...

Quote: Originally posted by Adrian Jones So, what are we supposed to refer to it as? 768 kps DTS?

Dts say DTS 768 and DTS 1536.

Quote: I remember a lot of complaining when the Matrix came out with 384 Kps Dolby Digital. I think there is generally quite a bit of complaining if the Dolby 5.1 is not 448 Kbps.

I was one on them. What I mean is that you never hear of people saying 'oh, it's only Dolby 2/3 rate', or words to that effect. Much more is made of the so-called 'half rate' DTS, when in fat it's still got a higher bitrate than ever the highest offering from Dolby.

The terms 'half-bitrate' is incorrect, or at least frowned upon. When do you ever hear people making the distinction between the different Dolby bitrates, even though it comes in 192, 256, 384 and 448Kbps flavours?

DTS is basically offered at either 768Kbps or 1536Kbps. The best soundtracks I've heard are typically 1536Kbps, but there are loads of kick-arse DOlby tracks around as well. It's not just a matter of encoding, it depends on the mix they actually encode to begin with.

Quote: Originally posted by Adrian Jones But, it is only half bit rate DTS. I have a few Superbits and I really can't tell any difference between the Dolby 5.1 and the half bit rate DTS tracks. The only DVDs where it is noticeable is on the ones with full bit rate DTS, like 12 Monkeys and Apollo 13.

What do you mean only half rate DTS? I do remember reading something about bitrates relating to DTS...like they were making a compromise. I thought The Bone Collector has a good DTS soundtrack...just to name one of my first. The train sounded like it was coming right in your living room. I compared it to the DD soundtrack which is certainly a few steps below the DTS track.

Video bit rate is influenced not only by the size/bit rate of an audio track, but the total number of audio tracks included on a DVD. It seems to me that region 3 discs usually contain a number of different language tracks, more so than other regions usually.

Quote: I have around 12 Superbit dvd,s. Only buy because original dvds don,t have DTS. Not interested in extras. Sell off old ones.

But, it is only half bit rate DTS. I have a few Superbits and I really can't tell any difference between the Dolby 5.1 and the half bit rate DTS tracks. The only DVDs where it is noticeable is on the ones with full bit rate DTS, like 12 Monkeys and Apollo 13.

Quote: Originally posted by Adrian Jones Is that because the originals were bad? How do the compare to other company's transfers. Sony's standard video transfers are usually below the standards set by the other major studios' releases. Their 'Stuporbit' titles are in line with what other companies give you without holding out on the special features. It is the worst of the current marketing gimmicks in the industry; if Sony wanted to treat their customers right they would just use the superior transfers on all of their releases. I will give them some credit for releasing a few, older catalog titles here as of late with the better transfers and extras, such as Leon and The Fifth Element, but such releases are too few and far between and they really should be releasing the majority of their catalog this way anyway.

Quote: Originally posted by Chris Gould They're nothing but a fucking sales gimmick. Columbia are guilty of providing sub-standard transfers for their standard DVDs (such as leaving more than 2GB of space on the disc) and then selling people Superbit as an upgrade.

Basically Superbit is no different to what most other studios do - i.e. put the movie on one disc and the extras on another. In short, Superbit is a cynical marketing gimmick that deserves to be ignored by the general DVD buying public.

They're nothing but a fucking sales gimmick. Columbia are guilty of providing sub-standard transfers for their standard DVDs (such as leaving more than 2GB of space on the disc) and then selling people Superbit as an upgrade.

Basically Superbit is no different to what most other studios do - i.e. put the movie on one disc and the extras on another. In short, Superbit is a cynical marketing gimmick that deserves to be ignored by the general DVD buying public.

Best Buy has all Superbit DVDs for $9.99. I don't own many Superbits, but was curious what everyone else thought about them. Are they mainly a marketing ploy? The Superbit Deluxe looks like the way to go, but I was checking out Snatch and it doesn't have the commentary track the regular release has. Are there any, "must have" Superbits?